The use of user equipment, including smartphones, cellular phones, laptops, digital pagers, mobile devices, among others, is becoming more prevalent. Many of these mobile devices have at least one cellular connection which may be used for both circuit switched and packet switched calls. Such cellular connection is usually based on a subscription or prepaid plan with a cellular provider.
In order to access the cellular provider's network, a smart card, such as a universal integrated circuit card (UICC), is typically found on such devices, where the UICC has one or more applications used for subscriber identity verification. Such applications may, for example, include a subscriber identity module (SIM) application or a universal subscriber identity module (USIM) application for the global system for mobile communications (GSM) networks, for a universal mobile telecommunications system (UMTS system) or long term evolution (LTE) system, a code division multiple access (CDMA) subscriber identity module application (CSIM application) for a CDMA 2000 network, a remote-user identity module (RUIM) for a CDMA network, International Mobile Services (IMS) subscriber identity module (ISIM) for IMS services, among others. Once authenticated to the network, the user equipment may then exchange voice or data, depending on the subscription with the cellular network.
Outside of the subscriber's home cellular network, the UE roams on to a visitor network. Authentication still occurs with the home network and agreements between the visitor network and the home network allow for the billing of the customer. This authentication computation occurs physically on the UICC, where the network and the UICC each maintain a shared secret for this computation. Typically such billing is relatively expensive compared to the services acquired from the home cellular network.